14.5 Evaluating code blocks

Code blocks can be evaluated1 and the results of evaluation optionally placed in the
Org mode buffer. The results of evaluation are placed following a line that
begins by default with #+RESULTS and optionally a cache identifier
and/or the name of the evaluated code block. The default value of
#+RESULTS can be changed with the customizable variable
org-babel-results-keyword.

By default, the evaluation facility is only enabled for Lisp code blocks
specified as emacs-lisp. However, source code blocks in many languages
can be evaluated within Org mode (see Languages for a list of supported
languages and Structure of code blocks for information on the syntax
used to define a code block).

There are a number of ways to evaluate code blocks. The simplest is to press
C-c C-c or C-c C-v e with the point on a code block2. This will call the
org-babel-execute-src-block function to evaluate the block and insert
its results into the Org mode buffer.
It is also possible to evaluate named code blocks from anywhere in an Org
mode buffer or an Org mode table. Live code blocks located in the current
Org mode buffer or in the “Library of Babel” (see Library of Babel)
can be executed. Named code blocks can be executed with a separate
#+CALL: line or inline within a block of text.

Arguments specified in this section will be passed to the code block. These
arguments use standard function call syntax, rather than
header argument syntax. For example, a #+CALL: line that passes the
number four to a code block named double, which declares the header
argument :var n=2, would be written as #+CALL: double(n=4).

<inside header arguments>

Inside header arguments are passed through and applied to the named code
block. These arguments use header argument syntax rather than standard
function call syntax. Inside header arguments affect how the code block is
evaluated. For example, [:results output] will collect the results of
everything printed to STDOUT during execution of the code block.

<end header arguments>

End header arguments are applied to the calling instance and do not affect
evaluation of the named code block. They affect how the results are
incorporated into the Org mode buffer and how the call line is exported. For
example, :results html will insert the results of the call line
evaluation in the Org buffer, wrapped in a BEGIN_HTML: block.

Footnotes

[1] Whenever code is evaluated there is a
potential for that code to do harm. Org mode provides safeguards to ensure
that code is only evaluated after explicit confirmation from the user. For
information on these safeguards (and on how to disable them) see Code evaluation security.

[2] The
option org-babel-no-eval-on-ctrl-c-ctrl-c can be used to remove code
evaluation from the C-c C-c key binding.